Vertical-crystalline Fe-doped beta-Ni oxyhydroxides for highly active and stable evolution reaction
- 전이금속이 도핑된 
-니켈 옥시하이드록사이드 기반의 알칼라인 전해질 산화극 촉매 개발
(Matter, 2021, 4, 3585-3604, IF: 15.589)
초록
The layered transition metal oxyhydroxides have received increasing interest owing to the efficient energy conversion performance and material stability during the oxygen evolution reaction (OER). In particular, Fe-doped NiOOH has shown record-high OER performance in alkaline media among various catalysts. Theoretically, undercoordinated facets including Ni4+, exposed at the edges of NiOOH, were predicted to perform highly active OER. Therefore, here we suggest a rational catalyst design, a vertical-crystalline beta-Fe/NiOOH layer built on faceted Fe/Ni nanocrystals, which exposes Ni4+ sites and could improve the OER performance dramatically. Electrochemical OER tests recorded the overpotential of 210 mV at a current density of 10 mA cm(-2) GEO and stable operation for 5 days. In situ/operando and density functional theory studies revealed that the Ni valence cycle between +2 and +4 assisted by Fe dopant is the key engine that greatly accelerates OER kinetics and that the vertical-crystalline beta-Fe/NiOOH layers on Ni octahedra are stable under harsh OER conditions.
본 연구에서는 실험적으로 니켈 원자들이 수직으로 배열된 결정구조를 가지는 
-니켈 옥시하이드록사이드 촉매를 합성하였으며 전이금속(Fe)이 도핑되는 경우 알칼라인 전해질에서 산소발생반응(OER)에 대한 촉매 성능이 증가하는 것을 확인하였다. 뿐만 아니라, 계산화학을 활용하여 니켈이 수직으로 배열된 구조와 Fe 도핑이 산소발생반응에 대한 촉매 반응성에 어떠한 영향을 끼치는지 규명하였다.